Tuesday would be – so the hype machine assured us – iPhone 5 day. But Tuesday came and went and it turned out to be only iPhone 4S day, and the assembled chorus drawn from the Apple-obsessed region of the blogosphere and the "analysts" of Wall Street howled their frustration. Which made one wonder what these people expected – an iPhone 5 that did teleportation? It also made one wonder if anyone on Wall Street has ever heard of the sigmoid function, the universal s-shaped learning curve that shows a progression from small beginnings and accelerates rapidly before creeping slowly towards its maximum point.

The point is that the iPhone has been through the acceleration phase and is now at the point where it can only get incrementally better. What CEO Tim Cook and his colleagues announced on Tuesday represented an implicit acknowledgment of that reality: they announced an incrementally improved product. But within that constraint they unveiled two significant developments that went under-reported by Apple-watchers – whose attention was soon diverted to the sad passing of Steve Jobs.

The first of these is the Siri natural language software that Apple is billing as an "intelligent personal assistant" to which one can issue instructions with a reasonable hope of getting an intelligent response. It uses natural language processing to answer questions, make recommendations and perform actions by delegating requests to other iPhone applications (calendar, email, text messaging, etc).

Siri has an interesting pedigree. It stems from a lavish research project funded by Darpa, the Pentagon agency that funds advanced research. It was eventually passed to the Stanford Research Institute, which in 2007 spun out a company (called Siri) that was acquired by Apple in 2010. The implication is that this isn't software created by a few geeks in a garage, but something that has had oodles of talent poured into it. Of course, as with all of this stuff, we'll have to see if it works as well in real life as it did in Tuesday's onstage demonstrations. But if it does, then other smartphone operators will find that the competitive bar has been raised by an unpalatable number of notches.

The launch of Siri on the phone also serves to highlight what was really significant about the device in the first place – namely that it was a powerful handheld computer that just happened also to make voice calls. The great paradigm-shifting insight that Steve Jobs and his team had was that voice was secondary to computing power. They reasoned that once they got that tiny platform into millions of consumers' hands, then all kinds of interesting things would be possible. Apps, for a start. And now formidable software, such as Siri, which needs computational horsepower in order to do its stuff.

The second "incremental" change in the iPhone 4S is the inclusion of an eight-megapixel camera with improved optics. Given that the iPhone 4 camera is already pretty good, you might have thought that this would be of interest only to photography nerds. Think again. There's an old saying that the best camera is the one you have with you, and everyone carries a phone, whereas most people don't carry a camera. If the phone also happens to have a good camera, then you can predict what will happen: the most popular camera among Flickr users is not anything made by Canon or Nikon, but the iPhone 4. The 4S model will just accelerate that trend.

Interestingly, the iPhone camera also highlights the importance of having substantial processing power. One of the most dramatic categories of photo app available for the device consists of programs that can provide high dynamic range (HDR) images. These are images of scenes where the contrast between shadows and highlights is too great for the camera sensor to handle: if the sunlit parts of the picture are properly exposed, then the rest of the image will be in shadow; and vice versa. HDR photography involves taking several pictures with different exposure times and then blending them into a composite image. Apps such as Pro HDR make the creation of these images such a breeze that one wonders why so few consumer cameras have this capability built in. The answer is that most digital cameras have puny processors, whereas the iPhone possesses the requisite horsepower.

Some observers of Tuesday's event remarked on how low-key and understated it was, compared to the usual Apple razzmatazz. With hindsight, the explanation is obvious. Tim Cook and co knew that the man who made all of this possible was slipping away. They remembered – as we do – his famous description of death as "life's change agent". That may be true, but it doesn't mean we can't mourn the loss of a truly extraordinary man.